@{$hash{$_}{file_contents}} = <FILE>;
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1. It's a good thing to put the local in a block (so ++), but with unexperienced users (the poster) it may be nice to note what it does. Well, the {local....} BLOCK restricts the scope of local to that block. So after the block, the $/ has it's original value (the line separator). One can read more about these and other vars in perlvar.
2. (Really tiny)The foreach was copied from the original post (and it works), but here is a for more precise. A foreach loop is used to change the contents of an array, for is not. So for reading in a file, I would recommend for. A typical use for foreach:

   @array = 0..100;
   foreach $item (@array){
     $item += 10 if $item <100;
   }
   print join "\n", @array; #prints the numbers 10 to 109 and 100
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   You can read more about it in for vs foreach.

Jeroen
"We are not alone"(FZ)
Update: For clarity, for and foreach *are* synonyms. It's just a matter of convention....

I tried the following:

#!/usr/local/bin/perl
use strict;

my @array = ('one', 'two', 'three');

for my $element (@array) {
        $element = uc($element);
}

for my $element (@array) {
        print "$element\n";
}

exit;
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The output was:
ONE
TWO
THREE

In this regard the for does in fact seem to be synonymous with foreach. In the extent that the elements of the array are changed both function the same.

But I must admit that by programming habit and for the sake of readiblity I adhere to the convention:

foreach loop to change the contents of an array
"for" when I'm not.

In spite of my habits and preferences apparently they both work the same. But alas my C background has me using for when I'm just stepping through array indexes.